The difference between a virus, a worm and a Trojan horse

Source: Internet
Author: User
Tags copy file system

With the increasing popularity of the internet, all kinds of viruses Trojan horse also rampant, almost every day there are new virus generation, wantonly spread destruction, to the vast number of Internet users caused a great harm, almost to the point of the poisonous color change. A variety of viruses, worms, Trojans in the pouring, it is impossible, distressed incomparable. So what exactly is a virus, a worm, a trojan, and what is the difference between them? I'm sure most people don't have a clear understanding of the problem, and here we have a brief talk.

Viruses, worms, and Trojan horses are malicious programs that can cause corrupted information on your computer and your computer. They can slow down your network and operating systems and even completely disrupt your system when you are in serious danger, and they may also use your computer to spread themselves to your friends, family, co-workers, and other parts of the Web, causing harm in a larger scope. These three kinds of things are man-made malicious code, will be harmful to the user, people often call them a virus, but in fact, this is not accurate, although they have a common, but there is a big difference.

What is a virus?

Computer virus (Computer Virus), according to the People's Republic of China regulations for the protection of computerized information systems, the virus is clearly defined as "refers to the establishment or in the computer program inserted in the destruction of computer functions or damage data, A set of computer instructions or program codes that affect the use of computers and can replicate themselves. A virus must meet two conditions:

1, it must be able to carry out its own. It usually places its own code in the execution path of another program.

2, it must be able to reproduce itself. For example, it might replace another executable file with a copy of a virus-infected file. A virus can infect both a desktop computer and a network server.

In addition, the virus often also has a strong infection, a certain degree of latency, specific triggers and a lot of damage, because the computer has these characteristics and biological viruses have similarities, because some people will this malicious program code called "Computer virus." Some viruses are designed to damage your computer by damaging programs, deleting files, or reformatting your hard disk. Some viruses do not damage computers, but simply copy themselves and indicate their presence by displaying text, video, and audio messages. Even these benign viruses can cause problems for computer users. Typically, they occupy the computer memory used by legitimate programs. As a result, it can cause an operation exception and even cause the system to crash. In addition, many viruses contain a large number of errors that can cause system crashes and data loss. Thankfully, in the absence of personnel operations, the general virus does not propagate itself, must be through a person to share files or send e-mail to move it together. The typical virus has black Friday virus and so on.

What is a worm?

Worms can also be regarded as one of the viruses, but there is a big difference between them and the common virus. It is generally believed that worms are a vicious virus spread through the network, it has some common characteristics of viruses, such as communication, concealment, destructive and so on, at the same time have their own features, such as not using the file parasitic (some exist only in memory), the network caused by denial of service, and the combination of hacker technology, and so on. Common viruses need to spread infected resident files for replication, and worms do not use resident files to replicate between the system, the common virus is mainly for the transmission of the file system within the computer, and worm transmission target is the internet all computers. It controls the ability to transfer files or information on a computer, and once your system is infected with worms, the worm can propagate itself, copying itself from one computer to another, and, more dangerously, replicating it massively. As a result of the destructive, worm virus is not the common virus can be compared to the development of the network so that the worm in a short time to spread the entire network, resulting in network paralysis! The shared folders, email emails, malicious web pages in the network, and a large number of servers with vulnerabilities in LAN conditions, Are a good way for worms to spread, worms can spread around the world in a few hours, and the aggressive and sudden outbreaks of worms will make people unprepared. In addition, the worm consumes memory or network bandwidth, which can cause the computer to crash. And its propagation does not have to be through "host" programs or files, so it can sneak into your system and allow others to remotely control your computer, which also makes it much more harmful than the common virus. The typical worm virus has Nimda, concussion wave and so on.

What is a Trojan horse?

Trojan Horse (Trojan horse), named after the "Trojan horse" in Greek mythology, the Greeks hid many Greek soldiers and lured the Trojans to transport them into the city in a huge Trojan disguised as a cult, and when the soldiers of the horse's belly liyingwaige with the soldiers outside the town, they breached the city of Troy. And now the so-called Trojan Horse refers to those who are ostensibly useful software, the actual purpose is to endanger computer security and cause serious damage to computer programs. It is a deceptive document (claiming to be benign, but is in fact malicious), a hacker tool based on remote control, with features of concealment and non authorization. The so-called concealment refers to the Trojan designer in order to prevent Trojan was found, will use a variety of means to hide the trojan, so that even if the server found infected with the Trojan, it is difficult to determine its specific location; the so-called "unauthorized" means that once the control end is connected to the server, the control end will steal many operational rights to the server, such as modifying the file, Modify the registry, control the mouse, keyboard, steal information and so on. Once in the Trojan, your system may be open to the door, there is no secret to say. The major difference between Trojans and viruses is that a Trojan horse is not contagious, it does not replicate itself like a virus, and does not "deliberately" infect other files, mainly by disguising itself to attract users to download and execute. Trojan horses contain malicious code that can cause data loss or even theft when triggered, and for the Trojan to propagate, these programs must be enabled effectively on the computer, such as opening e-mail attachments or bundling the Trojan in the software onto the web for attractive download execution. Now the Trojan is generally mainly to steal user-related information for the main purpose, relative to the virus, we can simply say that the virus destroys your information, and Trojans steal your information. Typical Trojan horses are gray pigeons, net silver thieves and so on.

From the above, we can know that in fact, ordinary viruses and some kinds of worms and all the Trojans are unable to propagate themselves. The common way to infect viruses and Trojans, one is to run infected with the virus Trojan program, one is to browse the Web page, mail was exploited browser vulnerabilities, virus trojan Automatic download run, this is basically the most common two types of infection. So to prevent viruses Trojan, we should first be vigilant, do not easily open dubious documents, websites, mails, and so on, and to timely patch the system, and finally installed on the firewall also has a reliable anti-virus software and timely upgrade virus library. If you do the above points, basically can eliminate the vast majority of viruses Trojan. Finally, it is worth noting that can not rely too much on anti-virus software, because the virus always appears in the anti-virus software before the upgrade, rely on anti-virus software to prevent viruses, itself is in a passive position, we want to have a safe network security environment, fundamentally still need to improve their own network security awareness, the virus to do prevention, Killing supplemented.

Contact Us

The content source of this page is from Internet, which doesn't represent Alibaba Cloud's opinion; products and services mentioned on that page don't have any relationship with Alibaba Cloud. If the content of the page makes you feel confusing, please write us an email, we will handle the problem within 5 days after receiving your email.

If you find any instances of plagiarism from the community, please send an email to: and provide relevant evidence. A staff member will contact you within 5 working days.

A Free Trial That Lets You Build Big!

Start building with 50+ products and up to 12 months usage for Elastic Compute Service

  • Sales Support

    1 on 1 presale consultation

  • After-Sales Support

    24/7 Technical Support 6 Free Tickets per Quarter Faster Response

  • Alibaba Cloud offers highly flexible support services tailored to meet your exact needs.